MUTEX_LOCK(_FOREACH_ENTITY_FIND_##T##_##id##mutex); \
entity _foundchain_first = _findchain##T##_tofield(fld, match, _FOREACH_ENTITY_FIND_##T##_next##id); \
FOREACH_LIST(_foundchain, _FOREACH_ENTITY_FIND_##T##_next##id, cond, body); \
MUTEX_UNLOCK(_FOREACH_ENTITY_FIND_##T##_##id##mutex); \
MUTEX_LOCK(_FOREACH_ENTITY_FIND_##T##_##id##mutex); \
entity _foundchain_first = _findchain##T##_tofield(fld, match, _FOREACH_ENTITY_FIND_##T##_next##id); \
FOREACH_LIST(_foundchain, _FOREACH_ENTITY_FIND_##T##_next##id, cond, body); \
MUTEX_UNLOCK(_FOREACH_ENTITY_FIND_##T##_##id##mutex); \